curiously, i came across this pic showing the four alchemical color stages in reverse order (no gold involved):
http://en.m.wikipedia.org/wiki/File:Iodine-triphenylphosphine_charge-transfer_complex_in_dichloromethane.jpg

iodine is relatively rare, but can be had from oceans and brine.
anyway, lots of interesting related items. i think someone posted on this before. if so, i'll remedy it when i get to a real computer.